1. Field of the Invention
The present invention relates to a heating device for use in heating a semiconductor wafer and the like.
2. Description of the Related Art
In a manufacturing process of a semiconductor device, a heating process is implemented for a wafer in order to form an oxidation film and the like on the wafer by using a semiconductor manufacturing apparatus. As an example of a heating device for implementing the heating process in the semiconductor manufacturing apparatus, there is a ceramic heater including a disc-like ceramic base having a heating surface on which a heated object is set, in which a resistance heating body is embedded in the ceramic base. The resistance heating body of the ceramic heater is embedded in the ceramic base. Electric power is supplied to the resistance heating body, whereby the resistance heating body allows the heating surface to generate heat.
The ceramic heater as described above is required to be capable of heating the wafer as the heated object so that the wafer can be stably maintained at a predetermined heating temperature. Moreover, the ceramic heater is required to be capable of uniformly heating the entire surface of the wafer. Accordingly, as the ceramic heater, there is one in which the contrivance is made for planar wiring of the resistance heating body and one in which a bulk-like heat sink as a temperature control member is attached onto a surface on the other side of the heating surface in the disc-like ceramic base, and the like. The bulk-like heat sink can dissipate the heat rapidly from the ceramic base. Therefore, a local temperature rise of the heating surface can be suppressed. This contributes to the uniform heating in the heating surface.
There is a heating device in which the bulk-like heat sink and the ceramic base are bonded to each other, for example, by an adhesion layer of silicon resin. However, heat resistance of the silicon resin is low, and the operation temperature of the heating device is limited. Moreover, the silicon resin is inferior in thermal conductivity, and accordingly, there are limitations on such uniformly heating all over the surface of the wafer and maintaining.
In this connection, there is a heating device in which the bulk-like heat sink and the ceramic base are bonded to each other by a bonding layer formed by thermal compression bonding of an aluminum alloy (Japanese Patent Laid-Open Publication No. H9-249465 (published in 1997)).
However, even by the heating device having the bonding layer formed by the thermal compression bonding of the aluminum alloy, the in-plane uniformity of the heating temperature of the heating surface of the ceramic base has not been sufficient. In particular, when an amount of the incoming heat to the resistance heating body is increased, and when the ceramic base is formed of a material having low thermal conductivity, the heating uniformity (uniform heating performance) has not been sufficient, and hence, uniformity of a surface temperature of the wafer heated by the heating device has not been sufficient. If the uniformity of the surface temperature of the wafer is not sufficient, then uniformities of deposition and etching in the surface, which are implemented for the wafer, are not sufficient, resulting in a decrease of manufacturing yield of the semiconductor device.
The purpose of the present invention is one to solve the above-described problems advantageously. The present invention will provide a heating device that improves the uniform heating performance on the heating surface, thus making it possible to heat uniformly a heated object supported onto the heating surface.